Tuesday, March 22, 2016

Madcow Bomarc Build, Part 3, Engine Mount

The assembly of the motor mount is standard, but heavier duty.
The engine hook got a few wraps of electrical tape.
The rear plywood centering ring is notched for engine hook movement.
The forward ring has a notch on the outside for the braided Kevlar.

Here's a drawing I did for the new Madcow instructions.
To see the posted instructions, CLICK HERE
The braided yellow Kevlar is tied around the top of the engine mount. The line goes through the notch in the upper ring.
A yellow glue fillet goes over the Kevlar wrap and the overhand knot.

The yellow Kevlar is tied to the white nylon shock cord with a simple overhand knot.
For now, the end of the Kevlar is taped to prevent it from unraveling.


  1. Nice build and instructions Chris. Check step 24. ;) I can't wait to see this fly.

  2. Okay, I have to ask a question that's been burning in my brain for some time now. Why do you use electrical tape as an engine hook retainer? Electrical tape turns gummy and soft when it gets hot, and even if that never happens it turns gummy and soft anyway in just a few years. When I'm not provided with a mylar retaining ring or making a centering ring do double duty, I put a bead of glue around the tube and then wrap the glued tube in crochet cotton (got a spool of a neutral tan at a thrift store for 50 cents, but even a new spool is cheap and goes a LONG way). Glued non-synthetic string is STRONG, probably stronger than mylar, and it will outlast most of the rest of the rocket.

    1. Hi Chris,
      I started using electrical tape after I opened up a few models that were only a few years old. The masking tape was dry and cracking off.
      I read somewhere else about using electrical tape and it seemed a good choice.
      The electrical tape might get gummy when it gets hot, I might see that on a hot Quest engines. For now, the mounts and tape are holding up well.
      Your glue and crochet cotton string method might be an all around solution. Some older Estes kits use a cardstock strip glued over the engine hook.